The invention relates to an inductive charging system for a vehicle. Specifically, the invention relates to the design of an inductive charging station.
Vehicles with an electric drive system are typically equipped with a battery, in which electrical energy for the operation of an electric motor of the vehicle can be stored. The vehicle battery can be charged using electrical energy from an power supply network. To this end, the battery is coupled to the power supply network, such that the electrical energy is transmitted from the power supply network to the vehicle battery. The coupling can be effected by hard-wiring (using a charging cable) and/or wirelessly (by way of inductive coupling between a charging station and the vehicle).
One approach to the automatic and wireless inductive charging of the vehicle battery is that electrical energy is transmitted to the battery by magnetic induction from the ground surface to the underbody of the vehicle via the underbody space 120. An exemplary representation is shown in FIG. 1. Specifically, FIG. 1 represents a vehicle 100 with a store 103 for electrical energy (e.g. with a chargeable battery 103). The vehicle 100 incorporates a “secondary coil” in the vehicle underbody, wherein the secondary coil is connected to the store 103 via an unrepresented impedance adaptor and a rectifier 101. The secondary coil is typically a component of a “Wireless Power Transfer” (WPT) vehicle unit 102.
The secondary coil of the WPT vehicle unit 102 can be positioned above a primary coil, wherein the primary coil is arranged e.g. on the floor of a garage. The primary coil is typically a component of a “WPT floor unit” 111. The primary coil is connected to a power supply 110 (in the present document, designated as a charging unit 110). The power supply 110 can include a radio-frequency generator, which generates an AC (alternating current) in the primary coil of the WPT floor unit 111, whereby a magnetic field is induced. In the present document, this magnetic field is designated as an electromagnetic charging field. The electromagnetic charging field can exhibit a predefined charging field frequency range. The charging field frequency range may lie within a frequency range of e.g. 80-90 kHz (specifically 85 kHz).
In the event of adequate magnetic coupling between the primary coil of the WPT floor unit 111 and the secondary coil of the WPT vehicle unit 102, the magnetic field induces a corresponding voltage, and thus a current, in the secondary coil via the underbody space 120. The current induced in the secondary coil of the WPT vehicle unit 102 is rectified by the rectifier 101 and is stored in the energy store 103 (e.g. in the battery). Accordingly, electrical energy can be transmitted wirelessly from the power supply 110 to the energy store 103 of the vehicle 100. The charging process can be controlled in the vehicle 100 by a charging control device 105 (also designated as the WPT control device 105). To this end, the charging control device 105 can be designed for communication, e.g. wirelessly, with the charging unit 110 (e.g. with a wallbox).
As a result of the limited underbody space 120, the potential dimensions of a WPT floor unit 111 are typically restricted. The dimensions of the WPT floor unit 111 can be reduced, e.g. by the transfer of certain components from the WPT floor unit 111 to the charging unit 110. However, this arrangement may be associated with higher specifications in respect of a connecting cable 112 between the floor unit 111 and the charging unit 110.
The present document addresses the technical issue of the design of a WPT floor unit 111, by means of which a reduction in the dimensions of the WPT floor unit 111, and a simplification of specifications for the connecting cable 112 between the floor unit 111 and the charging unit 110, can be achieved.
This and other objects are achieved in accordance with embodiments of the present invention. According to a first aspect, a floor unit (specifically a WPT floor unit) is described, which is designed for the generation of an electromagnetic charging field for the transmission of electrical energy to a vehicle (specifically a vehicle with an electric drive system). The vehicle may be a private car, a heavy goods vehicle and/or a motorcycle. The floor unit may be an element of a charging station which, in addition to the floor unit, includes a charging unit (e.g. a wallbox) which is connected to the floor unit by way of a connecting cable.
The floor unit includes a first interface, which is designed for the reception or take-up of electrical energy in the floor unit in the form of a direct current. The connecting cable can particularly be connected to a charging unit via the first interface on the floor unit. Accordingly, the floor unit can be designed for the take-up of a DC (direct current) at an input to the floor unit (i.e. at the first interface).
The floor unit also includes an alternating current generator (designated in the present document as a HF (high-frequency) generator), which is designed for the conversion of direct current into an alternating current. The alternating current is typically at the same frequency as the electromagnetic charging field which is generated by the floor unit. For example, the alternating current may exhibit a frequency of 80-90 kHz (specifically 85 kHz).
The floor unit also includes a primary coil, which is designed for the generation of the electromagnetic charging field from the alternating current.
The floor unit is thus designed for the generation of the electromagnetic charging field on the basis of a direct current at the input to the floor unit. Accordingly, it is possible for direct current to be transmitted from the charging unit via the connecting cable to the floor unit, thereby simplifying specifications for the connecting cable. At the same time, the floor unit incorporates no components for the generation of direct current from an power supply network and/or for Power Factor Correction. These components can be arranged in the charging unit. Accordingly, the floor unit can be configured in as compact a form as possible.
The floor unit can also incorporate a sensor which is designed for the detection of measuring data with respect to a state of the floor unit. For example, a temperature of the floor unit and/or the presence of a foreign body in the vicinity of the floor unit can be detected. Moreover, the floor unit can incorporate a communication unit, which is designed for the transmission of data, based upon measuring data, to the charging unit. As described above, the charging unit can be designed for the delivery of electrical energy to the floor unit in the form of a direct current. Specifically, the charging unit can be designed to deliver electrical energy in accordance with data received.
The communication unit can be designed for the constitution of a wireless communication link (e.g. a WLAN connection) to the charging unit, specifically with a corresponding communication unit in the charging unit. Alternatively or additionally, the communication unit of the floor unit can be designed for the constitution of a Power Line Communication (PLC) link to the charging unit, specifically via the power line of the connecting cable. The connecting cable thus requires no dedicated signal line for the transmission of data from the floor unit to the charging unit (or vice versa). Specifications and costs associated with the connecting cable can be simplified and reduced accordingly.
The floor unit can incorporate a control unit. The control unit can be designed to control the generation of alternating current by the alternating current generator. Specifically, the control unit can be designed for the reception of instructions from the charging unit (via the communication unit of the floor unit). The control unit can then control the generation of alternating current in accordance with the instructions received.
The floor unit can incorporate a second interface (and, where applicable, further interfaces). The second interface can be designed for the routing of electrical energy in the form of a direct current to another floor unit. Accordingly, a plurality of floor units can be connected in series or in a cascade arrangement. This is advantageous, as it permits one charging unit to supply a plurality of floor units. Costs for charging stations with a plurality of parking places can be reduced accordingly.
According to a further aspect, a charging unit for a charging station is disclosed for the wireless transmission of electrical energy to a vehicle. The charging unit incorporates a Power Factor Correction (PFC) unit, which is adapted to electrical energy from a power supply network in order to provide a direct current. The power supply network may deliver an AC (alternating current). The PFC unit can incorporate a rectifier, in order to generate a direct current from the AC current delivered by the power supply network, which direct current can then be delivered to a floor unit via a first interface on the charging unit.
The charging unit also incorporates a first interface, which is designed for the delivery of electrical energy to a floor unit in the form of a direct current. The first interface on the charging unit can be connected to a first interface on the floor unit by way of a connecting cable, in order to transmit electrical energy from the charging unit to the floor unit. The supply of a direct current permits the use of a cost-effective and flexibly-configurable connecting cable. Moreover, by the arrangement of the PFC unit in the charging unit, the size of the floor unit can be reduced. Accordingly, a PFC unit can be used for a plurality of floor units, thereby permitting costs for a charging station with a plurality of parking spaces to be reduced.
The charging unit can incorporate a plurality of interfaces, which are designed to deliver the electrical energy in the form of a direct current to a corresponding plurality of floor units.
As illustrated above, this permits the provision of a cost-effective charging station with a plurality of charging spaces.
The charging unit can incorporate a communication unit, which is designed to communicate with the vehicle and with the floor unit (or, where applicable, with a plurality of floor units). The communication unit can be designed for the constitution of a wireless communication link (e.g. WLAN) and/or a Power Line Communication (PLC) link. Accordingly, dedicated signal lines in the connecting cable can be omitted.
The charging unit can incorporate a control unit, which is designed to control the transmission of electrical energy to the vehicle via the floor unit. To this end, instructions can be transmitted via the communication unit to the one or more floor units.
According to a further aspect, a charging station for the wireless transmission of electrical energy to a vehicle is disclosed. The charging station incorporates a charging unit as described in the present document, which is designed for the delivery of electrical energy in the form of a direct current to a first interface on the charging unit. Moreover, the charging station incorporates at least one floor unit as described in the present document, which is designed for the take-up of the electrical energy in the form of a direct current at a first interface on the floor unit, and the generation therefrom of an electromagnetic charging field for the transmission of electrical energy to the vehicle. The charging station can also include a connecting cable, which is designed for the galvanic connection of the first interface on the charging unit with the first interface on the floor unit.
It should be observed that the methods, devices and systems described in the present document can be applied both in isolation, and in combination with other methods, devices and systems described in the present document. Moreover, any aspects of the method, device and systems described in the present document can be mutually combined in a variety of ways.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.